1. Field of the Invention
The present invention relates to a front structure of an automotive vehicle body.
2. Description of the Related Art
A pair of right and left front frames (front side frames) as main components of a front structure of an automotive vehicle body as recently frequently used in the art are curved inwardly of the vehicle body as extending rearwardly of the vehicle body, so as to allow the steering movement of front wheels in turning the vehicle and to obtain a sufficient turning radius even when a large engine is mounted on the vehicle. As shown in FIG. 1 which is a plan view of such a front structure in the related art, a pair of right and left front frames 2 is curved inwardly of the vehicle body as extending rearwardly of the vehicle body, and they are integrally connected at their rear ends to right and left floor frames 4, respectively.
Reference numeral 6 denotes a dashboard for partitioning a front compartment 7 and a cabin. The front compartment 7 includes an engine/transmission mounting space 8 for mounting an engine and a transmission. Since the front frames 2 are curved inwardly of the vehicle body as extending rearwardly of the vehicle body, the steering movement of front wheels 10 does not interfere with the front frames 2 in turning the vehicle, thereby allowing good turning performance. Furthermore, even when a large engine is mounted on the vehicle, a sufficient turning radius can be obtained.
The structure of each front frame 2 curved inwardly as mentioned above will now be described with reference to FIGS. 2A and 2B. FIG. 2A is a plan view of each front frame 2, and FIG. 2B is a cross section taken along the line 2B-2B in FIG. 2A. Each front frame 2 is composed of a front frame body 2a curved inwardly of the vehicle body as extending rearwardly of the vehicle body, and a closed section forming plate 2b spot-welded to the front frame body 2a. As shown in FIG. 2A, the front frame 2 is curved inwardly by the distance L1. Such a front frame constitutes a main energy absorbing member for absorbing energy by axial crush deformation in receipt of a front collision input to the vehicle, and various structures of such a front frame and its surroundings have been proposed.
In the conventional structure shown in FIGS. 2A and 2B, the front frame 2 is curved inwardly of the vehicle body as extending rearwardly of the vehicle body. Accordingly, the front frame body 2a is required to have a sufficient plate thickness. Furthermore, when a front collision input shown by an arrow 12 is applied to the front frame 2, a bending moment 14 acts on the front frame 2, and an impact force upon front collision is transmitted along curved ridge lines as shown by an arrow 16. As a result, the front frame 2 is easy to deform upon front collision.
For example, Japanese Patent Laid-Open No. 2003-118640, Japanese Patent Laid-Open No. 2002-316666, or Japanese Patent No. 3610938 discloses a straight front frame extending in the longitudinal direction of a vehicle, and the above-mentioned problem of a curved front frame is not recognized at all in these patent documents. Further, Japanese Patent No. 2958091 is an invention mainly intended to prevent the deformation of a front frame, thereby maintaining the impact absorbing performance of the front frame, and the above-mentioned problem of a curved front frame is not recognized at all also in this patent documents.